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Analysis of the results of regional mapping, integrated with new regional subcrop maps, has yielded significant regional concepts regarding the development of the frontier sedimentary basins west of Ireland. Five provinces of basement and Devono-Carboniferous rocks are mapped across the region. The nature of the basement successions, together with their inherent lineaments and structural fabrics, exerted a major influence on the location and structural segmentation of the basins and in acting as a conduit for Early Cretaceous and Early Cenozoic igneous activity. The major structures in the Porcupine region were N–S throughout its Late Palaeozoic to Cenozoic history, while those in the Slyne, Erris, Rockall and probably Hatton basins were predominantly NNE–SSW to NE–SW. The main structural controls in the Goban region were orientated ENE–WSW and NNW–SSE. The Porcupine Basin is shown to have a more pronounced N–S orientation than has hitherto been proposed. In particular, the basement core of the Porcupine High is shown to extend southwards to the Goban province, thereby isolating the basin for most of its history from the Atlantic region to the west. Separate Permo-Triassic to Jurassic basins occur on the flanks of the main, younger Rockall Basin and their location and orientation were influenced by NE–SW to ENE–WSW structural fabrics. Permo-Triassic sedimentation took place in a series of rift basins in the Porcupine, Rockall, Slyne–Erris and Goban regions. Jurassic rifting was widespread in most of the basins, commencing in Middle Jurassic time in the Slyne Basin but later (Late Jurassic) in the Porcupine and Rockall basins. Early Cretaceous sedimentation was more pronounced in the Porcupine and Rockall basins and shows less control by deep-seated structures. Late Jurassic to Early Cretaceous basin margin uplift on the flanks of the Rockall Basin in particular, is likely to explain the thin to absent nature of such strata in some of the adjacent smaller basins.

Marineg ravity andmagnetic surveys aroundI reland, togetherw ithsatelliteg ravity dataf rom the deepero cean,a reused to investigatethe large-scalec rustals tructureofthe PorcupineB asin,offshorewest of Ireland.The structureofthe syn-rifttopost-riftsedimentary successions,derived from verticalincidence seismic reflection data, isused to isolatethe gravity andmagnetic responsesofthe crust andmantle.The crustalstructure derived from wide-angleseismic datainthe region isused to control the interpretation andmodelling.The results ofgravity modellinginthe southern part ofthe PorcupineBasinsuggest acrustalthickeninginthe centreofthe basin. Comparison withthe Rockall Basin,wherea xialcrustalt hickeningi ss eismicallydefined, suggests a similarp attern ofc rustalextension. The amount ofe xtension isl ess across the narrowern orthern sector ofthe PorcupineB asin,whereanorth-south-trendinga xialgravity high isp resent resultingf rom anomalous density variations int he lowercrust/upperm antle.Anewm odelfor the large-scalestructuraldevelopment ofthe PorcupineB asinisp resented thatexplains the along-axisv ariationsincrustals tructurei nt erms ofc hangesin the kinematicsofcrustalextension across NW-SEtransferzones. Thismodelinvolvestectonic unroofingofthe mantlelithosphereandserpentinization ofthe exhumed mantleperidotites.

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The Irish offshore contains a large number of Late Palaeozoic to Cenozoic sedimentary basins, most of which are only lightly explored. These are grouped into the Irish Sea, Celtic Sea and Atlantic Margin basins. The basins developed in response to multi‐phase rifting which preceded the development of the North Atlantic Ocean. The major rift phases occurred during the Permo‐Triassic, Late Jurassic and Early Cretaceous. The Irish Sea basins contain a preserved succession of predominantly Permo‐Triassic and Early Jurassic age, with younger strata largely absent due to Cretaceous and Tertiary inversion. The Celtic Sea basins have a thick series of Triassic to Cretaceous strata, overlain by a generally thin Tertiary succession. The Atlantic Margin basins have a variable sedimentary thickness, with the larger basins characterized by a thick Tertiary succession. Two gasfields are currently in production in the North Celtic Sea Basin, while a number of undeveloped oil and gas accumulations have been discovered in both the North Celtic Sea Basin, and the Porcupine Basin on the Atlantic margin. A wide range of reservoir and source‐rock horizons have been encountered in the various basins. Most of the exploration to date has concentrated upon structural traps, but the recent resurgence of exploration interest is centred mostly upon a variety of stratigraphic traps, especially at Cretaceous and Tertiary levels, similar to successful plays further along strike in the UK and Norwegian sectors of the Atlantic Margin.

Comparative predictions of the end of construction performance of a central core embankment dam located in southern Portugal are presented. The predictions are based on finite element analyses, one set being carried out at Swansea and the other at the Laboratório Nacional de Engenharia Civil (LNEC) in Lisbon. Except for collaboration over the interpretation of laboratory test results the work was independent. Different analytical models were used at the two centres: the ‘KG’ model at Swansea and one based partly on the ‘hyperbolic’ model of Duncan and Chang at LNEC. The analytical work leading to the predictions was completed by the early stages of the dam's construction thus making them class A. The Paper starts with a description of a four-year laboratory research programme at LNEC to determine the properties of the fill materials. This involved novel large-scale one-dimensional and triaxial testing. Predictions of settlements and total stresses from the two models are presented at instrument locations. Useful comparisons between the models are obtained. This Paper will be followed later with a Technical Note comparing predictions and measurements. L'article présente des prévisions comparatives du comportement à la fin de la construction d'un barrage en terre avec un noyau central au Portugal du sud. Ces prévisions sont basées sur des analyses par éléments finis effectuées d'un côté à Swansea et de l'autre côté au Laboratôrio Nacional de Engenharia Civil (LNEC) à Lisbonne. Ces deux recherches étaient indépendantes l'une de l'autre, à l'exception d'une collaboration dans l'interprétation des résultats des essais faits en laboratoire. On a utilisé des modèles analytiques différents, le modèle K–G à Swansea et un modèle basé en partie sur le modèle hyperbolique de Duncan et Chang au LNEC. Les prévisions étaient de catégorie A, parce qu'on a complété le travail analytique qui les a précédées au cours des premières étapes de la construction du barrage. L'article commence par décrire le programme de recherches dans le laboratoire qui a été suivi pendant quatre années au LNEC pour déterminer les propriétés des matériaux de remblayage. Cette procédure comprenait de nouveaux essais unidimensionnels et triaxiaux de grand envergure. Des prévisions de tassements et de contraintes totales déduites des deux modèles sont présentées pour les emplacements des instruments et des comparaisons utiles sont obtenues. On a l'intention de publier plus tard une note technique qui comparera les prévisions et les mesures.

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